Improvement in screws



' UNITED STATES PATENT Orr'rc-E.

VILLIAM G. A. BONVILL, OF DOVER, DELAVARE.

IMPROVEMENT IN SCREWS.

Specification forming part of Letters Patent No. 45,133, dated November22, 1864.

To all whom it may concern:

Be it known that I, vVILLIAn G. A. BON- wILL, ot' Dover, in the countyot' Kent and State of Delaware, have invented a new and usefulImprovementin Wood-Screws 5 and I do hereby declare the following to bea full and exact description of the same, reference being had to theaccompanying drawings, making part ot' this specication, in which-Figure l is a side elevation, on an enlarged scale, of my improvedscrew. Fig. 2 is a transverse section ot' the same.

Similar letters of reference indica-te corresponding parts in theseveral figures.

My present invention relates to a wood-screw constructed in such mannertliatit may be inserted into or through the most delicate articlewithout splitting or otherwise injuring the same and it is also adaptedto be driven with less force, and to remain in a more tirin and securecondition within the wood wit-hout first boring a hole therefor.

In order that others skilled in the art to which my invention appertainsmay be enabled to fully understand and use the saine, I will proceed todescribe it.

In the accompanying drawings, A may represent the body of a screw, and Athe head thereof. In the threads ot' the screw A, I form one or moregrooves, a., each of which at the side a may be straight or radial, orslightly undercut, and the opposite side, a?, of the groove is beveled,the chief object in thus forming the screw being to prevent thesplitting of the wood into which it is driven without iirst boring ahole to receive it. The groove a may be spiral or diagonal or parallelwith the axis of the screw, and it may extend longitudinally the entirelength of the body A, including that portion near the head which is notthreaded, so as to provide free egress for the cuttings or particlesmade by the boring action ot' the screw. At the point a3 the groove acan be cut either level with the body of the screw or below it, so thatthe base will present a cuttiiig-edge as well as the thread. Byextending the groove a to the extreme point, as shown in Fig. 3, thescrew, after receivin g a very slight tap, will enter the wood as wellas a gimlet-pointed screw, although the difference between the point ofthe gimlet and that exhibited in Fig. 3 is readily distinguishable. Nearthe point of the screw I make the grooves parallel with the axis,whereas the girnlet-point. has a spiral groove which causes theparticles of wood to be pressed or forced asunder by the point whentapped with a hammer, and thus said gimletpoint is ineftectual, in thatit does not take a firm hold at the beginning of its insertion.

I have found by experiment that by making the grooves at the pointparallel with the axis the screw, when slightly tapped, will take atirni, wedge-like hold upon the wood, and when turned penetrate thesaine with an effect or action similar to that ot' an auger or ot a bit,cutting its way as it enters. The edge ti of the groove a may be eithercoincident with the general exterior ofthe screw, or, if desired, it maybe made somewhat prominent.

The principle upon which this screw is constructed, andjts superiority,as compared with those hitherto devised, will be readily perceived. Ascrew as constructed by me bores or cuts its way smoothly as fast as itpene- A trates, thus obviating resistance to its penetration, andadapting it to be driven by the application of but very little force,whereas the ordinary screw has great resistance oiered to itspenetration, for the reason that the threads, instead ot' cutting thewood, merely press the. fibers or particles into a smaller compass, evenwhen an aperture has been previously made for the reception ot' thescrew by an awl or other instrument. As it requires less force to drivethe screw when provided with a groove or grooves in the inannerexplained, it is in nowise more liable to break or bend than the screwin common use, and if in using my improved screw an aperture be firstmade for its reception, it will provide a more edectual attachingmedium, inasmuch as the wood preserves its normal condition and thethreads therein cut to the full depth.

Eithera straight, diagonal, or spiral groove, will serve to prevent thewood from splitting, and adapt the screw to enter with less resistance,Src.; but in practice I prefer to form the groove in such manner thatthe breaks in the thread will not be directly beneath or in line witheach other.

By extending the grooves into the body of the screw throughout its fulllength there will be more certainty of the holes being cleanly cut thefull 'thickness or diameter ofthe screw and freer egress given to thecuttings while i Having thus described my invention, what the screw ispenetrating, so that in ver.;r large I claim as new, and desire tosecure by Letters 'Screws this provision will e'eetually prevent Patent,is-

both splitting and choking. The groove may As a new article ofmanufacture, a woodalso be extended into jche beveled side of Jche screwconstructed as herein specified. head ofthe screw, (for the purpose ofadapting l it to countersink itself,) :is shown in Fig. l. W M (1" A'BON WILL' I am aware that; it has before been proposed Witnesses to formscrews with longitudinal or spiral HENRY W. DRAPER,

grooves intersecting the thread 5 but, ALBERT CowGILL.

